As a general rule, a motor vehicle suspension system comprises a suspension strut supporting an axle and a vehicle wheel. A suspension thrust bearing device is disposed in an upper portion of the suspension strut, opposite to the wheel and the ground, and between a suspension spring and an upper support block attached to the body of the vehicle. The device includes at least one rolling bearing. The suspension thrust bearing enables transmission of axial forces between the spring and the body of the vehicle and, in the meantime, allows relative angular movement between the spring, which is mobile in rotation, and the fixed support block attached to the body.
To this end, the spring is supported by a spring seat provided on the suspension thrust bearing. More precisely, the suspension thrust bearing comprises a lower support surface resting on ending coils of the spring. The spring support surface comprises a radial surface to support axial force. The spring support surface may also comprise a tubular axial surface to support radial deformations and to ensure the spring centering.
It is known to provide a damping device axially and radially disposed between the spring and the spring support surface of the suspension thrust bearing. As shown in these documents, the damping device is attached and/or integrated to the lower surface of the suspension thrust bearing. Damping device is made from a resilient material, such as rubber, thermoplastic elastomer (TPE), in particular thermoplastic polyurethane (TPU), melt processible elastomer (MPE) or elastomer cellular foam.
The damping device can be a separate component assembled in place by hand as part of the spring support surface. Alternatively, the damping device can be directly molded onto the spring support surface. Nevertheless, shocks and vibrations exerted by the spring during the use of vehicle can disassembled the damping device from the suspension thrust bearing.
The document US 2010/0014792 A1 proposes annular grooves supported by the spring seat, the damping device comprising a corresponding shape fitted within the grooves. However, the damping device and the spring seat may relatively rotate one to the other. The damping device material is softer than the spring seat and then it could be worn.
The document EP 2 152 531 B1 discloses longitudinal grooves blocking the rotation of the damping device. Furthermore, the longitudinal grooves comprise flaring side walls so as to prevent radial movement of the damping device. However, such grooves have a relative complex design.
Another disadvantage of the prior art documents is that radial and axial ends of damping device can separate from support surface. Mechanical cling, in particular by grooves and pins, and chemical cling, in particular by overmolding, between damping device and support surface are not robust enough in case of heavy torque, stress, and/or load. Damping device may separate at least locally from support surface, with the consequence of inefficient damping of spring and, in the worst case, relative rotation between the damping device and support surface.